Plants Obtained by Breeding
In the selection of plants for resistance to pests over the past 30-50 years, hybridization, or the cross-breeding of two or more varieties, differing in genetic basis, began to be widely used.
During hybridization in hybrid plant forms, many economically valuable traits are combined with hereditarily fixed traits of resistance to harmful organisms.
Distinguish between spontaneous (natural) and artificial hybridization. Natural hybridization is carried out independently in nature, and artificial hybridization is used by humans and is an effective method of plant breeding. Artificial hybridization is carried out in order to obtain offspring with a new combination of genetically determined traits. Hybridization allows the breeder to combine a number of forms of resistance to individual harmful species or to different types of pests and diseases in one variety. When selecting pairs for hybridization, the Mendelian rules for the inheritance of desired characters serve as a theoretical basis. All hybrid plants in the first generation (F1) are genetically identical, but they are homozygous or heterozygous for individual resistance genes, which depends on the genetic structure of the parents. The splitting of these signs occurs. in the second (F2) and subsequent generations. Therefore, during selection, plants of the second generation are selected from the hybrid population, characterized by a greater degree of severity of their resistance to harmful organisms and other economically valuable traits.
There are several categories of hybridization: intraspecific, interspecific and intergeneric.
Intraspecific crosses are crosses of plant forms belonging to the same species (subspecies, varieties, lines, clones). When plants are selected for harmful organisms by the method of intraspecific crosses, highly resistant plant forms identified within this species are used. When choosing donors of pest resistance, it is necessary that the plants, if possible, combine the attributes that apply to all three well-known resistance groups (rejection, antibiosis and endurance).
When carrying out intraspecific crosses, barriers of incompatibility between different plant forms do not arise. Crosses are successful, and hybrid offspring are characterized by a fairly high fertility.